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Stefan Seelecke - One of the best experts on this subject based on the ideXlab platform.
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planning for flexible surgical robots via bezier spline translation
International Conference on Robotics and Automation, 2019Co-Authors: Johannes Fauser, Romol Chadda, Yannik Goergen, Markus Hessinger, Paul Motzki, Igor Stenin, Julia Kristin, Thomas Klenzner, Jörg Schipper, Stefan SeeleckeAbstract:In a minimally invasive surgery, new flexible instruments enable safer and easier access to difficult-to-reach anatomical regions. However, their introduction into the clinical workflow requires robust replanning because navigation errors during surgery render initially planned trajectories infeasible. Such replanning requires to regularly solve an expensive two-point boundary value problem (BVP) that connects the target pose of the instrument with the currently measured one. We propose a hybrid planning scheme that features both robust and safe replanning. This two-step approach first solves the BVP and then transforms the result to circular arcs that fit the motion of our instruments’ models. We exploit implicitly defined Bezier splines as a robust method for interpolation in the first step. A novel geometric translation of these splines, then, provides a convenient solution for movement along circular arcs. We consider two example applications: 1) planning for a Drilling Unit in temporal bone surgery; and 2) guidewires in catheter insertion. Evaluation on real patient data of both temporal bone and aorta show that our proposed hybrid two-step approach achieves, on average, ${\text{55}\%}$ higher replanning rates and provides ${\text{31}\%}$ larger clearance to risk structures, thus improving trajectory quality with regard to clinical safety.
Guttorm Grytoyr - One of the best experts on this subject based on the ideXlab platform.
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wellhead fatigue analysis method
ASME 2011 30th International Conference on Ocean Offshore and Arctic Engineering, 2011Co-Authors: Torfinn Hørte, Morten Saether, Guttorm GrytoyrAbstract:Re-completion and re-Drilling of existing wells and introduction of new large Drilling rig systems are elements that have led to renewed focus on the fatigue capacity for existing and new subsea wells. Due to lack of applicable codes and standards for such fatigue calculations, a unified analysis methodology has been developed and described in a Wellhead Fatigue Analysis Method Statement (MS). The intention of this work is to reflect the best practice in the industry and to provide an important contribution to well integrity management. The analysis methodology is limited to fatigue damage from dynamic riser loads present during subsea Drilling and work over operations. The analysis procedure may be divided into three parts. i) A local response analysis that includes a detailed finite element model from wellhead datum and below. Interaction between the structural well components and soil structure interaction is properly accounted for. The main result from this analysis is the load-to-stress curve that describes the relationship between the riser loads at the wellhead datum and the stress at the fatigue hot spots. The analysis also provides the lower boundary conditions of the global load analysis model. ii) A global load analysis where the floating mobile Drilling Unit (MODU) motions and wave loads on the riser are taken into account. The results are time series or load histograms of the loads at wellhead datum, with focus on the bending moment, in all relevant environmental sea states. iii) Fatigue damage assessment, where a mapping of the loads with the relevant load to stress curve is carried out together with subsequent fatigue damage calculation. Appropriate S-N curve is applied together with wave scatter diagrams for the relevant operations and durations. The final result is the accumulated fatigue damage. With a unified analysis methodology in place particular attention is placed on a structured and specified analysis input and output. Results are suggested presented as a function of time and also as a function of key analysis input parameters that are associated with uncertainty. These are prerequisites from a well integrity management perspective in ensuring analysis results that are comparable. This paper presents the essence of the Wellhead Fatigue Analysis Method that was developed in cooperation between Statoil and DNV. Currently this analysis methodology is under extension and revision in the joint industry project (JIP) “Structural Well Integrity During Well Operations”. 11 operators participate in this JIP which also has structured cooperation with equipment suppliers, Drilling companies and analysis houses. The aim is to form a wellhead analysis recommended practice document.Copyright © 2011 by ASME
Jianliang Zhou - One of the best experts on this subject based on the ideXlab platform.
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comprehensive risk assessment of deepwater Drilling riser using fuzzy petri net model
Process Safety and Environmental Protection, 2018Co-Authors: Yuanjiang Chang, Xiangfei Wu, Jihua Ye, Liangbin Xu, Guoming Chen, Bin Chen, Jianliang ZhouAbstract:Abstract Drilling risers are the critical connection of subsea wellhead and the floating Drilling Unit. With exploration and development of oil and gas resources moving into deepwater, Drilling riser operations have been characterized with high safety risk and occurrence rate of accidents causing high Drilling downtime and Drilling cost. In the present study, a Fuzzy Petri Net (FPN) methodology is proposed to evaluate the comprehensive risk of deepwater Drilling risers. A risk index evaluation system was established based on analyses of Drilling riser accidents and identification of risk factors, and the AHP-EM method was used to determine the weights of them. A 9-tuple set was defined to model Drilling riser risks according to the FPN theories, and by using the fuzzy reasoning algorithm, risk values of risk factors at different levels and the integrated system were gained by iteration of state matrix. A specific case study of deepwater Drilling risers of NANHAI-8 Drilling Unit in Liuhua oilfield in South China Sea is presented to illustrate the application of proposed approach, and some suggestions drawn from the investigation are presented to further mitigate the risk of Drilling riser operations. The case study showed that FPN is a practical and reliable method in comprehensive risk evaluation of deepwater Drilling riser system.
Paul Ashcroft - One of the best experts on this subject based on the ideXlab platform.
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analysis of environmental and economic damages from british petroleum s deepwater horizon oil spill
Albany law review, 2010Co-Authors: Lawrence C Smith, Murphy Smith, Paul AshcroftAbstract:ABSTRACT This study examines the environmental and economic damages caused by British Petroleum's CBP") Deepwater Horizon oil spill in the spring and summer of 2010. (1) The process of oil exploration and production is extremely challenging, offering significant rewards that are offset by equally significant risks. The world's demand for energy is constantly growing, thereby leading to extraordinary efforts and gigantic investments by energy companies to find new supplies of oil. The $365 million Deepwater Horizon was an offshore Drilling Unit designed to operate in waters as deep as 8000 feet, and to drill down 30,000 feet. (2) The Deepwater Horizon was Drilling an exploratory well about forty-one miles off the coast of Louisiana, when on April 20, 2010, an explosion killed eleven workers and began the release of massive amounts of oil into the Gulf. (3) The well was eventually capped on July 15. (4) Total damages to BP, the environment, and the U.S. Gulf Coast economy are estimated to be $36.9 billion. (5) The damages are attributed to three major factors: (1) human error and equipment failure at BP's Deepwater Horizon offshore Drilling Unit; (2) failure of the U.S. government to assign, and in some cases to permit, resources to assist with the containment of the oil spill; and (3) misinformation disseminated by the news media regarding the amount and location of oil pollution in the water and on the beaches of the Gulf of Mexico. ANALYSIS OF ENVIRONMENTAL AND ECONOMIC DAMAGES FROM BP's DEEPWATER HORIZON OIL SPILL A. Introduction In the spring and summer of 2010, the BP Deepwater Horizon oil spill dominated the world news. The event was hailed as an environmental and economic disaster. World energy needs are constantly growing, resulting in extraordinary efforts and gigantic investments by energy companies to find new supplies of oil. Oil exploration and production is well known for its tremendous challenges, working in harsh environments, and using the latest and most complex technologies. Successful operations can lead to significant rewards, but these are offset by equally significant risks. The purpose of this paper is to examine the environmental and economic damages caused by BP's Deepwater Horizon oil spill in the spring and summer of 2010. The Deepwater Horizon was an offshore Drilling rig, licensed to BP by Transocean Ltd. (6) The Deepwater Horizon was a fifth-generation dynamic positioned semi-submersible oil rig. (7) The Deepwater Horizon cost $365 million to build, and was designed to operate in waters as deep as 8000 feet, and to drill down 30,000 feet. (8) The Deepwater Horizon was Drilling an exploratory well about forty-one miles off the coast of Louisiana, when on April 20, 2010, an explosion and fire killed eleven workers and began the release of massive amounts of oil into the Gulf of Mexico. (9) The oil spill was ultimately contained when the well was capped on July 15, 2010. (10) Damages to BP, the environment, and the U.S. Gulf Coast economy are estimated to be $36.9 billion, as will be described in this paper. (11) The damages are ascribed to three major factors: (1) human error and equipment failure at BP's Deepwater Horizon offshore Drilling Unit; (2) failure of the U.S. government to assign, and in some cases to permit, resources to assist with the containment of the oil spill; and (3) misinformation disseminated by the news media regarding the amount and location of oil pollution in the water and on the beaches of the Gulf of Mexico. B. Background and Past Research People's concern for the environment can be traced back to ancient times. (12) Directions for proper care of the natural environment are found in ancient literature, such as the Bible and Qur'an. The Prophet Moses, known mostly for providing the Ten Commandments, also gave the ancient Israelites guidance regarding land management and care of animals. (13) The Prophet Mohammed offered instructions concerning water conservation in the Holy Qur'an. …
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analysis of environmental and economic damages from british petroleum s deepwater horizon oil spill
2010Co-Authors: Lawrence C Smith, Murphy Smith, Paul AshcroftAbstract:This study examines the environmental and economic damages caused by British Petroleum’s Deepwater Horizon oil spill in the spring and summer of 2010. The process of oil exploration and production is extremely challenging, offering significant rewards that are offset by equally significant risks. The world’s demand for energy is constantly growing, thereby leading to extraordinary efforts and gigantic investments by energy companies to find new supplies of oil. The $365 million Deepwater Horizon was an offshore Drilling Unit designed to operate in waters as deep as 8,000 feet and to drill down 30,000 feet. The Horizon was Drilling an exploratory well about 41 miles off the coast of Louisiana, when on April 20 an explosion killed 11 workers and began the release of massive amounts of oil into the Gulf. The well was eventually capped on July 15. Total damages to BP, the environment, and the US gulf coast economy are estimated to be $36.9 billion. The damages are attributed to three major factors: (1) human error and equipment failure at BP’s Deepwater Horizon offshore Drilling Unit, (2) failure of the US government to assign, and in some cases to permit, resources to assist with the containment of the oil spill, and (3) misinformation disseminated by the news media regarding the amount and location of oil pollution in the water and on the beaches of the Gulf of Mexico.
Yuanjiang Chang - One of the best experts on this subject based on the ideXlab platform.
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comprehensive risk assessment of deepwater Drilling riser using fuzzy petri net model
Process Safety and Environmental Protection, 2018Co-Authors: Yuanjiang Chang, Xiangfei Wu, Jihua Ye, Liangbin Xu, Guoming Chen, Bin Chen, Jianliang ZhouAbstract:Abstract Drilling risers are the critical connection of subsea wellhead and the floating Drilling Unit. With exploration and development of oil and gas resources moving into deepwater, Drilling riser operations have been characterized with high safety risk and occurrence rate of accidents causing high Drilling downtime and Drilling cost. In the present study, a Fuzzy Petri Net (FPN) methodology is proposed to evaluate the comprehensive risk of deepwater Drilling risers. A risk index evaluation system was established based on analyses of Drilling riser accidents and identification of risk factors, and the AHP-EM method was used to determine the weights of them. A 9-tuple set was defined to model Drilling riser risks according to the FPN theories, and by using the fuzzy reasoning algorithm, risk values of risk factors at different levels and the integrated system were gained by iteration of state matrix. A specific case study of deepwater Drilling risers of NANHAI-8 Drilling Unit in Liuhua oilfield in South China Sea is presented to illustrate the application of proposed approach, and some suggestions drawn from the investigation are presented to further mitigate the risk of Drilling riser operations. The case study showed that FPN is a practical and reliable method in comprehensive risk evaluation of deepwater Drilling riser system.
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non linear dynamic response induced by wave current for marine risers with guide frames
Journal of China University of Petroleum, 2006Co-Authors: Yuanjiang Chang, Guoming Chen, Liangbin XuAbstract:Considering the gap-contact condition between guide-frames and the fixed Drilling Unit riser subjected to wave-current loads, the solution method for transient dynamic problem under the nonlinear boundary condition was discussed. By applying the finite element method, the marine riser was modeled as the beam model which was fixed under the seabed mudline at the depth of three meters, simply supported at the lower deck, and its lateral vibration was restricted by guide-frames at different elevation. Using ANSYS software, the gap-contact condition between marine riser and guide-frames was simulated by combination40 element. The non-linear dynamic response of marine riser under one-hundred-year wave-current environmental load was calculated, the displacement-time history of typical nodes and equivalent stress-time history of typical elements were also obtained, and strength check of the riser was then achieved successfully. The results provide reference for design and analysis of the marine risers with guide-frames.
